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CBSE Questions for Class 12 Engineering Chemistry Biomolecules Quiz 2 - MCQExams.com
CBSE
Class 12 Engineering Chemistry
Biomolecules
Quiz 2
Sulphur is required in plants, as a nutrient element for:
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making hormones
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absorption of water
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making vitamins
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absorption of fat
Explanation
Plants require sulphur to produce vitamins, amino acids, enzymes, and proteins
Which of the following is the correct statement?
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Starch is a polymer of $$\alpha$$- glucose.
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Amylose is not a component of starch.
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Proteins are composed of only one type of amino acid.
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In cyclic structure of fructose, there are five carbon and one oxygen atoms.
Explanation
Starch is a polymer of $$\alpha$$-glucose
When alpha-glucose molecules are joined chemically to form a polymer, starch is formed.
Which of the following is an acidic amino acid ?
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Glycine
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Valine
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Leucine
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Glumatic acid
Explanation
Two amino acids have acidic side chains at neutral pH. These are aspartic acid or aspartate (Asp) and glutamic acid or glutamate (Glu). Their side chains have carboxylic acid groups.
Among the following essential amino acid is:
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alanine
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valine
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proline
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serine
Explanation
Valine is an essential amino acid which is used in the synthesis of proteins. It consists of a $$\alpha$$-amino group, a
$$\alpha$$-carboxyl group, and a side chain isopropyl group, making it a nonpolar amino acid
Vitamin A is present in ?
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fish liver oil
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milk
0%
butter
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all of these
Explanation
Vitamin A is present in liver, milk, green and yellow vegetables and yellow fruits, such as broccoli, spinach, turnip greens, carrots, squash, sweet potatoes, pumpkin, apricots, cod liver oil and in animal sources such as liver, milk, butter, cheese, and whole eggs etc.
Hence, the correct option is D.
Which one of the following bases is not present in DNA?
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Thymine
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Quinoline
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Adenine
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Cytosine
Explanation
Quinoline is an alkaloid, it is not present in DNA. DNA has four nitrogen bases i.e. adenine (A), guanine (G), cytosine (C) and thymine (T).
Vegetable oils like wheat germ oil, sunflower oil, etc. are the good source of ?
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vitamin K
0%
vitamin E
0%
vitamin D
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vitamin A
Explanation
Vitamin E is found in vegetable oils like wheat germ oil (135$$\%$$ DV per serving), sunflower oil (37$$\%$$ DV per serving) etc.
The elimination of H' will take place at
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(a)
0%
(b)
0%
(c)
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(d)
Which of the following is not produced by human body?
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Enzymes
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Vitamins
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Proteins
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Nucleic acid
Explanation
Vitamins are essential components of our diet and are not produced by our body.
Incorrect statement about given carbohydrate is
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Above compound is a reducing sugar
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Above compound undergo mutaritation
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Above compound is a non-reducing sugar
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Above compound has a glycosidic linkage
Explanation
As the given compound contains free $$OH$$ group at anomeric carbon. So it can act as reducing again in its open chain configuration thats why it is reducing sugar.
Guanine is an example of:
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a nitrogenous base
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a nucleoside
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a nucleotide
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phosphate
Explanation
The four nitrogenous bases present in DNA are adenine (A), guanine (G), cytosine (C) and thymine (T).
The vitamin having metal atom is
?
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Vitamin A
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Vitamin K
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Vitamin $${ B }_{ 12 }$$
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Vitamin C
Explanation
The vitamin having metal atom is
Vitamin B$$_{12}$$(
cobalamin) as it contains a metal ion (cobalt).
$$\textbf{Additional Information}$$
It is also called cyanocobalamin
Vitamin
B$$_{12}$$
contributes to the formation of red blood cells and bone marrow, the metabolism of carbohydrates, fats and proteins and the production of genetic materials.
Vitamin
B$$_{12}$$
is mainly present in animal products, such as meat, poultry, fish, eggs, seaweed, and to a lesser extent in milk and dairy products.
An example of a disaccharide is:
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Glucose
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Ribose
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Cellulose
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Lactose
Explanation
Lactose is made of 1 unit of glucose and 1 unit of galactose. So, it is a disaccharide.
Which of the following is a polysaccharide?
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Cellulose
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Sucrose
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Galactose
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Maltose
Explanation
Cellulose is a polysaccharide. Cellulose is a linear polysaccharide polymer with many glucose monosaccharide units.
It is an organic compound with the formula $$(C_6H_{10}O_5)_n$$. The cellulose chain bristles with polar $$-OH$$ groups. These groups form many hydrogen bonds with $$OH$$ groups on adjacent chains, bundling the chains together. The chains also pack regularly in places to form hard, stable crystalline regions that give the bundled chains even more stability and strength.
A disaccharide which gives only glucose on hydrolysis is :
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lactose
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fructose
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sucrose
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maltose
Explanation
Lactose is made of glucose and galactose.
Fructose is itself a monosaccharide.
Sucrose is made of glucose and fructose.
Maltose is made of 2 glucose units.
So, D is correct.
Carbohydrates containing more than $$10$$ simple units of sugar are called:
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Monosaccharides
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Disaccharides
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Trisaccharides
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Polysaccharides
Explanation
Oligosaccharide gives three to ten (3-10) molecules of monosaccharides on hydrolysis.
Polysaccharides gives a large number of molecules of monosaccharides on hydrolysis.
Hence, the correct option is $$\text{D.}$$
The carbohydrates are classified on the basis of:
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sugars and non-sugars
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reducing character
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optical activity
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hydrolysis
Explanation
The correct statements are I, II and IV only.
The carbohydrates are classified on the basis of:
I. Sugars and Non sugars : Sugars are crystalline, sweet to taste and water soluble. Non sugars are amorphous, tasteless and water insoluble.
II. Reducing character : Reducing carbohydrates and non reducing carbohydrates.
IV. Hydrolysis : monosaccharides, disaccharides, oligosaccharides and polysaccharides.
The carbohydrates are not classified on the basis of optical activity.
Option A, B and D are correct.
Which of the following is not a monosaccharide?
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Glucose
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Fructose
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Glyceraldehyde
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Sucrose
Explanation
Sucrose consists of a glucose and a galactose unit. So, it is a disaccharide and not a monosaccharide.
Which carbohydrate is used in silvering of mirrors ?
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Fructose
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Glucose
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Sucrose
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Starch
Explanation
Silvering
is the chemical process of coating glass with a reflective substance. In this process glucose is used to reduce the silver into silver nitrate when it is added on to the mirror.
Which disaccharide is present in milk?
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Maltose
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Galactose
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Sucrose
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Lactose
Explanation
Milk contains lactose. You must have heard of milk containing lactic acid, which is formed by the fermentation of lactose by bacteria.
Glucose is a/an:
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oxidising sugar
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reducing sugar
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both reducing and oxidising sugar
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none of the above
Explanation
Glucose is an aldose, which means that its open-chain form contains an aldehyde group. Aldehydes are quite easily oxidized to carboxylic acids. So a mild oxidizing agent will be reduced by glucose.
Proteins are polyamides of:
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$$\beta -$$ amino acids
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$$\alpha -$$ amino acids
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$$\alpha -$$ hydroxy acids
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$$\beta -$$ keto acids
Explanation
Proteins are natural polymers. They are large biological molecules consisting of one or more
chains of $$\alpha$$- amino acids.
A mixture of
$$\alpha$$
-amino acids is obtained when proteins are hydrolysed by:
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acids
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bases
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enzymes
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all of the above
Explanation
A mixture of $$\alpha$$-amino acids is obtained when proteins are hydrolysed by acids, bases and enzymes. Proteins are hydrolysed and broken down into its component amino acids. While there are many means of achieving this, two of the most common are prolonged boiling in a strong acid or strong base or using an enzyme such as the pancreatic protease enzyme to simulate the naturally occurring hydrolytic process.
The acidic amino acid is:
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Aspartic acid
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Alycine
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Serine
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Tyrosine
Explanation
An acidic amino acid contains more $$-COOH$$ groups than $$-NH_2$$ groups, which is the case of Aspartic acid among the given options.
The simplest carbohydrate is:
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dihydroxyacetone
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formaldehyde
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glucose
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sucrose
Which one of the following is $$\alpha$$-amino acid?
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$$NH_{2}C_{6}H_{5}-CH-CH_{2}-COOH$$
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$$NH_{2}-CH_{2}-CH_{2}-CH_{2}-CH_{2}-COOH$$
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$$NH_{2}-CH_{2}-COOH$$
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$$NH_{2}C_{6}H_{5}-CH-CH_{2}-CH_{2}-COOH$$
Explanation
$$NH_{2}-CH_{2}-COOH$$ is $$\alpha$$ amino acid, as the amino and carboxylate groups are attached to the same carbon atom.
Starch is converted into maltose by an enzyme:
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maltase
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zymase
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diastase
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invertage
Explanation
Starch is converted into maltose by an enzyme diastase. During this process, in this regime the diastatic enzymes start acting on the starches, breaking them up into sugars (hence the term saccharification). The amylases are enzymes that work by hydrolyzing the straight chain bonds between the individual glucose molecules that make up the starch chain. A single straight chain starch is called an amylose. A branched starch chain (which can be considered as being built from amylose chains) is called an amylopectin. These starches are polar molecules and have different ends.
In acidic medium, amino acid exists as:
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$$R-CH(NH_{2})COOH$$
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$$R-CH(NH_{3})^{+}COOH$$
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$$R-CH(NH_{2})COO^{-}$$
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$$R-CH(NH_{3})^{+}COO^{-}$$
Which of the following is a polysaccharide?
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Maltose
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Raffinose
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Glycogen
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Galactose
Explanation
Glycogen is a polysaccharide while maltose, raffinose and galactose are oligosaccharides.
Relation between amino acids and proteins is similar to the one present between
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nucleotides and nucleic acids
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RNA and DNA
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glucose and fructose
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all of the above
Explanation
Amino acids and proteins are similar to the nucleotides and nucleic acids. Just as proteins are made up of numbers of amino acids, similarly nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made from monomers known as nucleotides.
Starch is composed of two polysaccharides namely:
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amylopectin and glycogen
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amylose and glycogen
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amylose and amylopectin
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amylose and amylopectin and glycogen
Explanation
Amylose and amylopectin are polysaccharides of starch. Starches are glucose polymers in which glucopyranose units are bonded by $$\alpha$$-linkages. It is made up of a mixture of amylose (15%-20%) and amylopectin (80%-85%). Amylose consists of a linear chain of several hundred glucose molecules and Amylopectin is a branched molecule made of several thousand glucose units. Starches are insoluble in water. They can be digested by hydrolysis, catalyzed by enzymes called amylases, which can break the $$\alpha$$-linkages (glycosidic bonds).
Which of the following is pyrimidine base ?
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Adenine
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Guanine
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Uracil
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All the above
Explanation
Uracil
is pyrimidine base.
Pyrimidine is an aromatic heterocyclic organic compound similar to pyridine. Three types of nucleobases are pyrimidine derivatives: cytosine(C), thymine(T), and uracil(U). Uracil is present in RNA and thymine is present in DNA.
Purine derivative among the bases is:
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thymine
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uracil
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guanine
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cytosine
Explanation
Guanine is purine while guanine, cyotosine and uracil are pyrimidine.
Purines and Pyrimidines are nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA.
The two-carbon nitrogen ring bases (adenine and guanine) are purines, while the one-carbon nitrogen ring bases (thymine, uracil and cytosine) are pyrimidines.
Option C is correct.
Nucleic acids are constituents of:
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haemoglobin
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nucleoproteins
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all proteins
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only lipid proteins
Explanation
Nucleoproteins
are any proteins
that are structurally associated with nucleic acids,
either DNA
or RNA.
Typical nucleoproteins include ribosomes, nucleosomes
and viral nucleocapsid proteins.
In nucleic acids , the sequence is
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Phosphate base sugar
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Sugar phosphate base
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Phosphate-sugar base
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Base phosphate sugar
Explanation
In nucleic acids , the sequence is p
hosphate-sugar base.
Nucleic acids are polymeric macromolecules, or large biological molecules, essential for all known forms of life. Nucleic acids, which include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are made from monomers known as nucleotides. Each nucleotide has three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. If the sugar is deoxyribose, the polymer is DNA. If the sugar is ribose, the polymer is RNA.
In the nucleic acids, the phosphate ions are bonded with sugar at:
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5, 3 locations
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5, 2 locations
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3, 1 locations
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5, 1 locations
Explanation
In the nucleic acids, the phosphate ions are bonded with sugar at 5, 3 locations. The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphate diesters linkages.
The carbons to which the phosphate groups attach are the 3'-end and the 5'-end carbons of the sugar. This gives nucleic acids directionality, and the ends of nucleic acid molecules are referred to as 5'-end and 3'-end.
Nucleic acids are polymers of:
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Nucleotides
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Nucleosides
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Nuclei of heavy metals
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Proteins
Explanation
DNA and RNA are termed as nucleic acids.
They are polymers of nucleotides.
A nucleotide consists of a base, a sugar molecule and a phosphate molecule.
Each codon consists of how many nitrogen bases?
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four
0%
twenty
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three
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sixty four
Explanation
Each codon codes for 1 amino acids, which in turn, are made by the combination of 3 nitrogen bases.
Guanine is an example of:
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Nucleotide
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Nucleoside
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Purine base
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Pyrimidine base
Explanation
Guanine is an example of purine base.
Another example of purine base is adenine.
Cytosine thymine and uracil contains pyrimidine ring.
Option C is correct.
Assertion ( A): Thymine pairs with adenine whereas cytosine pairs with Guanine in DNA molecule .
Reason ( R ):The hydrogen bonding between bases of two strands is Highly specific .
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Both A and R are true and R is the correct explanation of A .
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Both A and R are true but R is not a correct explanation of A
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A is true but R is false
0%
A is false but R is true
Nucleic acids are
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small molecules
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polymeric in nature
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the compounds of C, H and O
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essentially proteins
Explanation
Nucleic acids include DNA and RNA. They are polymers of nucleotides (a base + a sugar ring and a phosphate molecule). So, B is correct.
Vitamin B$$_{1}$$ is known as:
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ascorbic acid
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carotenoids
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thiamine
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pyridoxine
Explanation
Vitamin $$B_1$$ is known as thiamine. It is a water soluble vitamin of B complex. It is important in carbohydrate (sugar and starch) metabolism, maintenance of normal growth, and transmission of nerve impulses.
Vitamin D is also known as:
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growth vitamin
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sunshine vitamin
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reproductive vitamin
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ascorbic acid
Explanation
Vitamin $$D$$ is also known as sunshine vitamin. This vitamin is mainly obtained from sun rays.
It is essential for growth of bones, helps the body to absorb calcium.
Option B is correct.
Nucleic acids are called acids mainly because of the presence of__________
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$$-COOH$$ group
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$$-OH$$ group of sugar unit
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$$-OH$$ group of the heterocyclic base
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$$-OH$$ group of phosphate unit
Explanation
Nucleic acids are called acids mainly because of the presence of $$-OH$$ group of phosphate unit.
The nucleic acids are linear unbranched polymer of purine and pyrimidine nucleotides linked in a chain through phosphodiester bonds.
Each nucleotide made up of a 5- carbon sugar (pentose), a nitrogenous base and phosphoric acid.
The acidic character of the nucleic acids is due to presence of the phosphoric acid.
Option D is correct.
Which of the following is a dicarboxylic acid with one double bond?
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Ethylene `
0%
Traumatic acid
0%
Absicic acid
0%
Auxins
Explanation
Traumatic acid is a dicarboxylic acid with one double bond. Its molecular formula is $$C_{12}H_{20}O_4$$. It is found in some plants and stimulates healing when a plant tissue undergoes trauma.
For artificial ripening of fruit, which of the following is used?
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Auxin
0%
Cytokinin
0%
Ethylene
0%
Gibberellin
Explanation
All of the given options are phytohormones (plant hormones).
Plant hormones control all the growth and development activities like cell division, enlargement, flowering, seed formation, dormancy and abscission. The major function of the given hormones are as follows:
A) Auxin- Cell elongation of stems and roots
B) Cytokinin- Promotes lateral and adventitious shoot growth by inducing cell division.
C) Ethylene- Hastens the ripening of fruits
D) Gibberellin- Breaks seed dormancy promotes flowering Hence, ethylene gas is used for the artificial ripening of fruits.
Which of the following vitamins is oil soluble?
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A
0%
B$$_{6}$$
0%
B$$_{12}$$
0%
B$$_{1}$$
Explanation
Vitamins $$A$$ is oil soluble vitamin while complex of vitamin $$B$$ are water soluble vitamins.
Option A is correct.
Which of the following vitamins is water soluble?
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0%
K
0%
E
0%
D
0%
B$$_{1}$$
Explanation
$$\bf{Hint:-}$$ Polar molecules are water-soluble.
$$\bf{Explanation-}$$
$$\bullet$$ Vitamins help in converting food into energy which is required for the body to perform work.
$$\bullet$$
There are many types of vitamin $$B$$. All the vitamins $$B_1, B_2, B_{12},$$ and $$B_6$$ are water-soluble vitamins because these are polar in nature as shown
below in
$$B_1$$ structure :
$$\bullet$$
Being water-soluble these are readily excreted through urine. These vitamins are not toxic to the human body. They cannot be stored in the body.
$$\bf{Conclusion-}$$
Thus, among all vitamin $$B_1$$ is water-soluble. Option $$D$$ is correct.
Which of the following substance acts as stimulator?
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vitamins
0%
enzymes
0%
hormones
0%
carbohydrates
Explanation
Hormones acts as stimulator. Hormones are essential for every activity of life, including the processes of digestion, metabolism, growth, reproduction, and mood control. Many hormones, such as neurotransmitters, are active in more than one physical process. To release active hormones quickly, hormone biosynthetic cells may produce and store biologically inactive hormones in the form of pre- or prohormones. These can then be quickly converted into their active hormone form in response to a particular stimulus.
Receptors of hormones are generally:
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carbohydrates
0%
vitamins
0%
lipids
0%
protiens
Explanation
Receptors of hormones are generally proteins.
Hormones affect distant cells by binding to specific receptor proteins in the target cell resulting in a change in cell function. When a hormone binds to the receptor, it results in the activation of a signal transduction pathway.
This may lead to cell type-specific responses that include rapid non-genomic effects or slower genomic responses where the hormones acting through their receptors activate gene transcription, resulting in increased expression of target proteins.
Option D is correct.
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